switch_root, tailf, uuidparse, waitpid: add pages

[gutjuri]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):

[vitorhcl]

Being part of util-linux, all commands are linux-exclusive, so we have to move them to linux/:

• About tailf: FreeBSD, NetBSD, OpenBSD and osx don't (neither didn't) have such command.
• switch_root, uuidparse and waitpid also don't have a manual page for FreeBSD, NetBSD, OpenBSD and osx.

[kbdharun]

LGTM, Thanks for your contribution.

[vitorhcl]

Looks good to me, thank you for your contribution! I have some suggestions.